I heard this song months before the movie, but having the spoilers, I really felt this song fit the movie to a T. However, it's not Anakin's feelings, but Obi-Wan's (in relation to what he had to do in letting go of Anakin). This is also likely an artist no one who follows this thread has ever heard of. She does a killer cover of "Wild Horses."

Up All Night
Charlotte Martin
from the album On Your Shore

It's 3 AM and I have been in my head for quite some time
Every fear, every tear has been swirling in my mind
And there are still a hundred reasons I shouldn't walk away
Do I love you if I leave you? You have no name...

I was up all night
Waiting for some kind of miracle
I was up all night
Feeling all alone in the universe
I was up all night

When morning comes I will tell you it's life I have to chase
But every song that I sing will be written by your face
And if you're really meant to be then you'll be back again
And I watch as your beginning turns into the end

I was up all night
Waiting for some kind of miracle
I was up all night
Feeling all alone in the universe
If it's you or if it's me I save
I'm still throwing it all away
I was up all night

With a kick inside in the dark you hide and we both know
how the end will be in your little tide with your eyes shut wide
and we both know how the end will be, how it will be

I was up all night
Waiting for some kind of miracle
I was up all night
Feeling all alone in the universe
If it's you or if it's me I save
I'm still throwing it all away
I was up all night
I was up all
(I'm bending until I break for you)
I was up all
(I'm bending until I break for you)
I was up all night
Night
Night

Smouldering decay
Take your breath away
Millions of our years
In minutes disappears

Darkening in vain
Decadence remains
All is said and done
Never is the sun

Never...!

FIRE
To begin whipping Dance of the Dead,
Blackened--is the--end!
To begin whipping Dance of the Dead....
FIRE
Is the outcome of hypocrisy,
Darkest--poten-CY!
In the exit of hu-ma-ni-ty,
Color our world Blackened!

Twenty-twenty-twenty four hours to go I wanna be sedated
Nothin' to do and no where to go-o-oh I wanna be sedated
Just get me to the airport put me on a planeHurry hurry hurry before I go insane
I can't control my fingers I can't control my brain
Oh no no no no no
Twenty-twenty-twenty four hours to go....
Just put me in a wheelchair and put me on a plane
Hurry hurry hurry before I go insane
I can't control my fingers I can't control my brain
Oh no no no no no
Twenty-twenty-twenty four hours to go I wanna be sedated
Nothin' to do and no where to go-o-o I wanna be sedatedJust put me in a wheelchair get me to the show
Hurry hurry hurry before I gotta go
I can't control my fingers I can't control my toes
Oh no no no no no
Twenty-twenty-twenty four hours to go...
Just put me in a wheelchair...
Ba-ba-bamp-ba ba-ba-ba-bamp-ba I wanna be sedated
Ba-ba-bamp-ba ba-ba-ba-bamp-ba I wanna be sedated
Ba-ba-bamp-ba ba-ba-ba-bamp-ba I wanna be sedated
Ba-ba-bamp-ba ba-ba-ba-bamp-ba I wanna be sedated

I think Battle of the Heroes, or any other piece of music from the film that John Williams decide to go with for depicting Anakin's feeling IN THE FILM
I trust his judgement on accompanying feelings with appropriate music.

Anyone ever hear of the great British '70s prog-rock outfit Van Der Graaf Generator. From their 1971 masterpiece Pawn Hearts, I give you...Man-Erg:

The killer lives inside me; yes, I can feel him move.
Sometimes he's lightly sleeping in the quiet of his room;
but then his eyes will rise and stare through mine,
he'll speak my words and slice my mind inside.
Yes, the killer lives.

The angels live inside me, I can feel them smile;
their presence strokes and soothes the tempest in my mind
and their love can heal the wounds that I have wrought.
They watch me as I go to fall;
well, I know I shall be caught
while the angels live.

How can I be free?
How can I get help?
Am I really me?
Am I someone else?

But stalking in my cloisters hang the acolytes of gloom
and Death's Head throws his cloak into the corner of my room
and I am doomed.
But laughing in my courtyard play the pranksters of my youth
and solemn, waiting Old Man in the gables of the roof:
he tells me truth.

And I, too, live inside me and very often don't know who I am;
I know I'm not a hero; well, I hope that I'm not damned.
I'm just a man, and killers, angels, all are these,
dictators, saviours, refugees in war and peace
as long as Man lives...

I'm just a man, and killers, angels, all are these:
dictators, saviours, refugees.

I think these lyrics (composed by the group's singer Peter Hammill) are just as good a way as any to describe the internal conflict between the Light and Dark Sides of the Force.